Aeromedical factorsQuestion 892 of 934

Which common over-the-counter ingredient causes drowsiness and stays in the body a long time?

  1. Acetylsalicylic acid
  2. Diphenhydramine
  3. Ibuprofen
  4. Caffeine
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Correct answer: Diphenhydramine

Drugs that contain diphenhydramine have a prolonged half-life, which lengthens the time of side effects.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 17: Aeromedical Factors — Drugs, page 438

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Questions last reviewed: 18 October 2026